Motorized skateboard with uni-directional rear mounting

Abstract

A skateboard comprises a rider's platform having pairs of front and rear wheels mounted thereunder. Front wheels are mounted for limited universal movement relative to the platform whereas the rear wheels are mounted under the platform solely for vertical pivot movements about a pivot axis disposed in a vertically disposed plane which intersects the longitudinal axis of the skateboard. A bracket is attached to the rear wheel mounting and has a motor secured thereon for selectively driving only one of the rear wheels via a stepped-down drive train and a centrifugally actuated clutch. A normally open kill-switch is mounted on a throttle control adapted to be grasped by a rider whereby a magneto of the engine may be grounded to stop the engine when desired.

I claim: 
     
       1. A skateboard comprising a horizontally disposed rider's platform,   a pair of laterally spaced front wheels connected beneath a forward end of said platform,   a pair of rear wheels,   mounting means connecting said rear wheels beneath a rearward end of said platform for solely permitting vertical pivotal movements of said rear wheels about a pivot axis disposed in a vertically disposed plane intersecting a longitudinal axis of said skateboard, said mounting means comprising a bracket assembly pivotally mounted beneath the rearward end of said platform and having said rear wheels rotatably mounted thereon and wherein said bracket assembly extends rearwardly from said rear wheels,   motor means, having an output shaft, mounted rearwardly on said bracket assembly and   drive means connecting the output shaft of said motor means with only one of said rear wheels for selectively driving the same comprising a first sprocket secured to the output shaft of said motor means, a countershaft rotatably mounted on said bracket assembly, a second sprocket secured to a first end of said countershaft, an endless first chain entrained about said first and second sprockets, a third sprocket secured to a second end of said countershaft, a fourth sprocket connectible with said one rear wheel and an endless second chain entrained about said third and fourth sprockets.   
     
     
       2. The skateboard of claim 1 wherein the pivot axis for said rear wheels is disposed at an acute angle relative to the longitudinal axis of said skateboard and is disposed to diverge relative thereto towards a forward end of said skateboard. 
     
     
       3. The skateboard of claim 1 wherein said angle is selected from the range of 10° to 45°. 
     
     
       4. The skateboard of claim 1 wherein said mounting means comprises a pin pivotally mounted on a mounting bracket secured beneath said platform and wherein the pivot axis for said rear wheels is defined by said pin. 
     
     
       5. The skateboard of claim 4 wherein mounting means further comprises a bracket assembly disposed beneath said platform and mounted on said pin and wherein said rear wheels are rotatably mounted on said bracket assembly. 
     
     
       6. The skateboard of claim 5 wherein said bracket assembly comprises a pair of longitudinally spaced first and second support brackets mounted on opposite ends of said pin and wherein said pin constitutes a bolt having a nut threadably mounted on one end thereof and disposed exteriorly of said first support bracket and elastomeric grommet means mounted on a second end of said bolt and disposed and compressed between said second support bracket and said mounting bracket. 
     
     
       7. The skateboard of claim 6 further comprising adjustment means for selectively adjusting the longitudinal disposition of said first support bracket relative to said second support bracket on said bracket assembly. 
     
     
       8. The skateboard of claim 7 wherein said bracket assembly further comprises a channel bar and wherein said adjustment means comprises an elongated slot formed through said channel bar and a bolt releasably securing said first support bracket to said channel bar for selectively adjusting the longitudinal position of said first support bracket relative to said second support bracket. 
     
     
       9. The skateboard of claim 1 further comprising adjustment means for selectively adjusting tensions on said first and second chains. 
     
     
       10. The skateboard of claim 1 further comprising centrifugally actuated clutch means operatively connectible between said third sprocket and said countershaft for driving said second chain when the speed of said countershaft exceeds a predetermined amount. 
     
     
       11. The skateboard of claim 1 further comprising throttle control means for selectively varying the speed of the output shaft of said motor means, including a pistol grip having a control lever pivotally mounted thereon and a control cable connected between said control lever and a throttle control lever of said motor means. 
     
     
       12. The skateboard of claim 11 further comprising switch means mounted on said pistol grip adapted to be connected to a magneto of said motor means for selectively actuating said motor means. 
     
     
       13. The skateboard of claim 1 wherein said motor means is secured to an upstanding mounting bracket detachably mounted on a side of said brackt assembly. 
     
     
       14. The skateboard of claim 13 further comprising adjusting means for selectively adjusting the longitudinal disposition of said mounting bracket on said bracket assembly. 
     
     
       15. A skatebaord comprising a horizontally disposed rider's platform,   a pair of laterally spaced front wheels connected beneath a forward end of said platform,   a pair of rear wheels,   mounting means connecting said rear wheels beneath a rearward end of said platform for solely permitting vertical pivotal movements of said rear wheels about a pivot axis disposed in a vertically disposed plane intersecting a longitudinal axis of said skateboard comprising a pin pivotally mounted on a mounting bracket secured beneath said platform and wherein the pivot axis for said rear wheels is defined by said pin and a bracket assembly disposed beneath said platform and mounted on said pin and wherein said rear wheels are rotatably mounted on said bracket assembly, said bracket assembly comprising a pair of longitudinally spaced first and second support brackets mounted on opposite ends of said pin and wherein said pin constitutes a bolt having a nut threadably mounted on one end thereof and disposed exteriorly of said first support bracket and elastomeric grommet means mounted on a second end of said bolt and disposed and compressed between said second support bracket and said mounting bracket, and   adjustment means for selectively adjusting the longitudinal disposition of said first support bracket relative to said second support bracket on said bracket assembly.   
     
     
       16. A skateboard comprising a horizontally disposed rider's platform,   a pair of laterally spaced front wheels connected beneath a forward end of said platform,   a pair of rear wheels,   a bracket assembly mounted beneath the rearward end of said platform and having said rear wheels rotatably mounted thereon and wherein said bracket assembly extends rearwardly from said rear wheels,   motor means, having an output shaft, mounted rearwardly on said bracket assembly, and   drive means connecting the output shaft of said motor means with one of said rear wheels for selectively driving the same comprising a first sprocket secured to the output shaft of said motor means, a countershaft rotatably mounted on said bracket assembly, a second sprocket secured to a first end of said countershaft, an endless first chain entrained about said first and second sprockets, a third socket secured to a second end of said countershaft, a fourth sprocket connectible with said one rear wheel and an endless second chain entrained about said third and fourth sprockets.